With advancements of mobile technology and positioning systems, user navigation using mobile devices has become a common practice. Currently, there are many mobile devices such as mobile phones, car navigation systems and the like, which have the ability to obtain the current geographical location using location evaluation technologies such as Global Positioning System (GPS) and signal strength based positioning systems.
Even though present navigation systems allow a mobile user to automatically obtain his/her (hereinafter male terms represents both genders) current position using technologies such as GPS, in general, navigation systems cannot automatically obtain users' destination, which is necessary for providing navigation service. In most of the conventional cases the mobile user set the destination by himself at an initial stage of the navigation process.
However, there are cases where the user does not know the exact geographical location of the destination or/and the route (the path from current location to the destination location including both current location and destination location). Moreover, the route provided by the system might not be an optimal solution which satisfies mobile users' need.
As an example, consider a case where a user is going to a friends' birthday party organized at his friends' house. A conventional navigation system may be providing the shortest route to his friends' house. However, in case user wanted to buy a present on the way to the friends' house, the user might want to choose a route that passes through a gift shop on the way to the destination (friends' house). Such a situation can be considered as a case where the conventional navigation systems are unable to provide a suitable route.
When above mentioned situations are considered, one of the most realistic solutions available for the mobile user is asking the route from a person (an assigned user) who already knows the destination or the route.
Even though there are known art that discuss location data information sharing among paired navigation terminals (see Japanese Patent Application Laid Open: 2002-22482), in general, conventional navigation systems do not provide a mechanism that allow direct modification of the route displayed on a mobile terminal by an assigned another user. Thus, users has to depend on another communication channel, which is separated from the navigation system, such as a telephone call, to communicate with the designated user by voice and modify his route by himself according to the designated users' instructions. However, this is not an effective or convenient method for a mobile user or a designated user.